Rafter Membrance Hold Down Clip

ABSTRACT

A hold down clip is installed on the rafters or a building to secure a membrane between the rafters before the roof is put on the building. The rafter hold down clip and membrane create an air gap between the rafters, thereby creating an insulation layer beneath the roof. The depth of the air gap is determined by the length of the legs of the rafter hold down clip. In a presently preferred embodiment of the invention, the legs are about 1.5 inches long, and therefore create an air insulation gap about 1.5 inches deep.

FIELD OF THE INVENTION

The present invention relates generally to the field of insulation for building such as residences and the like and, more particularly to a system for forming an air gap for insulation beneath the roof of a residence. This invention relates even more particularly to a hold down clip adapted to be affixed to a rafter in order to form such an insulating air gap.

BACKGROUND OF THE INVENTION

There has recently been an upsurge in interest in various types of insulation for all types of buildings, including dwellings. One reason for this increase in interest in insulation of various types is the drastic rise in energy costs, including the cost of heating oil and the cost of heating homes with other sources of energy.

One way to insulate a dwelling involves the installation of well known batt-type insulation. This type of insulation is commonly installed in the spaces between rafters and joists in roofs, floors, and walls. Many well known techniques have been used for the installation of this type of insulation, many of which are well described in U.S. Pat. No. 6,622,448 to Sonne, and incorporated herein by reference. Sonne teaches a batt insulation hold-down clip which has a U-shaped base for wrapping about the exposed edges of framing member used under roofs, ceilings, floors, and wall. The clips have side extending arms that abut against the insulation material and can include protruding portions which further press the insulation material in place. The drawback in this type of solution is that it requires the batt-type insulation. Furthermore, after installation, the vulnerable paper covering of the batt-type insulation is exposed and may be damaged by contact from within the dwelling.

Thus, there remains a need for a system for insulation of a dwelling that does not require such batt-type insulation and which is relatively immune to damage from contact from within the dwelling. The present invention is directed to filling this need in the art.

SUMMARY OF THE INVENTION

The present invention addresses these and other needs by providing a hold down clip which is installed on a rafter before the roof is put on a dwelling. This rafter hold down clip, when used in association with available attic wrap products, creates an air insulation gap between the rafters beneath the roof of a residence. The depth of the air insulation gap is determined by the length of the legs of the rafter hold down clip. In a presently preferred embodiment of the invention, the legs are about 1.5 inches long, and therefore create an air insulation gap about 1.5 inches deep.

The rafter hold down clip includes a flat horizontal plate which is retained in close, even abutting engagement with and on top of a rafter. The legs of the hold down clip extend downward from the flat, horizontal plate. The legs are bowed so that the wrap is held snugly against the sides of the rafter. The flat, horizontal plate is slightly wider than the width of the rafter, but the closest point between the bowed legs is less than the width of the rafter so that the wrap is retained in friction engagement between the hold down clip and the rafter.

These and other features and advantages of the present invention will be readily apparent to those of skill in the art from a review of the following detailed description along with the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of the rafter hold down clip of this invention.

FIG. 1B is a section view of the rafter hold down clip of FIG. 1A.

FIG. 2 is a section view of two, side by side rafters with hold down clips and wrap installed in accordance with the teachings of this invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring first to FIGS. 1A and 1B, there is illustrated a rafter hold down clip 10 of the present invention. The rafter hold down clip 10 comprises a substantially flat, horizontal plate 12, a first leg 14, and a second leg 16. The hold down clip 10 is preferably formed by extrusion of rigid polyvinyl chloride (PVC) and then cut to length, although other materials may be used. Thus, the plate 12, the first leg 14, and the second leg 16 are formed as an integral unit of manufacture.

The plate 12 defines a width w which is only slightly greater than the width of the rafter to which the hold down clip is to be installed, for example about 1.5 inches for a single width rafter. Each leg 14 and 16 defines a length l, which will ultimately determine the thickness of the air gap insulating layer provided by this invention, and shown and described below in greater detail. The hold down clip material is preferably about 0.062 inches thick to provide desired strength to hold the attic wrap material against the rafter.

Note particularly the shape of the legs 14 and 16. The legs bow inwardly to define a throat t, which is less than w, and in a preferred embodiment is about 1 inch. The throat provides a grip onto a rafter, and the portion of the legs below the throat flare outward. In other words, the first leg 14 has an end 50 and the second leg 16 has and end 52, and the ends 50 and 52 flare away from each other. The outward flare of the legs provides ease of installation of the hold down clip, but more importantly reduces the likelihood of the hold down clip tearing a wrap material as the hold down clip is being installed.

It should also be noted that the leg 14 forms a shoulder 20 with the plate 12 and that the leg 16 forms a shoulder 22 with the plate 12. The intersection of the leg 14 and the plate 12 defines an acute angle θ and the intersection of the leg 16 and the plate 12 defines an acute angle φ.

FIG. 2 shows the present invention as it is installed. A first hold down clip 10′ is installed on a first rafter 30 and a second hold down clip 10″ is installed on a second rafter 32. A durable, water resistant wrap material or membrane 34 is secured between the first hold down clip 10′ and the first rafter 30 and is secured between the second hold down clip 10″ and the second rafter 32. As illustrated in FIG. 2, the wrap material 34 is pulled taut between the hold down clip 10′ and the hold down clip 10″. This forms a air gap 36, defined by the wrap material 34, the hold down clips 10′ and 10″, and an overlying roof layer 38, usually of plywood or oriented strand board (OSB) or the like, or similar well known roofing material. The wrap material is preferably a durable, robust material formed of woven nylon, for example, but the defining characteristics of the wrap material are tear resistance, strength during the installation process, water resistance, and the ability to remain undegraded for the life of the roof, such as for example 30 years. These and other characteristics are met or exceeded by DuPont Tyvek AtticWrap. These terms are trademarks of Dupont.

To install the system of this invention, the builder first completes the framing work on the attic and roof space, including the installation of the rafters 30 and 32. To begin installing the rafter hold down clip insulation system of the present invention, the builder is first provided with a pre-cut six inch rafter hold down clip for each rafter tail. The rafter tail is the portion of the rafter which extends beyond the exterior wall of the building to define the eave of the residence. The builder then strikes a chalk line parallel to the eave edge, about 12-16 inches up from the each of the rafter tails to align the wrap material.

Next, the builder rolls out the wrap 34 a convenient length, for example about 6 feet. AtticWrap™ is provided with an adhesive layer, and the adhesive layer is preferably oriented at the top. The end of the sheet of wrap is then stapled to the first rafter properly aligned with the chalk line. As the wrap is unrolled, a hold down clip 10 is placed over each rafter in turn, with the wrap snugly stretched between the rafters. Preferably, the hold down clip 10 is then nailed or stapled to the rafter to hold the assembly securely to the rafter.

Once the first, relatively narrow strip of wrap material and hold down clips have been installed, the next higher layer of wrap is installed. The second and subsequent layers of wrap are preferably about four feet wide, and each layer preferably overlaps the previous layer. As previously described, the wrap material preferably includes an adhesive, facing up, and the overlapping layers are then sealed together to form an air tight seal, thereby providing an air gap insulation layer beneath the roof of the building.

The principles, preferred embodiment, and mode of operation of the present invention have been described in the foregoing specification. This invention is not to be construed as limited to the particular forms disclosed, since these are regarded as illustrative rather than restrictive. Moreover, variations and changes may be made by those skilled in the art without departing from the spirit of the invention. 

1. A rafter hold down clip for installation on a rafter of predetermined width, the rafter hold down clip comprising: a substantially flat plate; a first leg extending from and integrally formed with the flat plate and forming a first shoulder with the flat plate at a first acute angle; and a second leg extending from and integrally formed with the flat plate and forming a second shoulder with the flat plate at a second acute angle.
 2. The rafter hold down clip of claim 1, wherein the plate defines a width which is greater than the width of the rafter.
 3. The rafter hold down clip of claim 1, wherein the first and second legs bow toward each other.
 4. The rafter hold down clip of claim 1, wherein the first leg defines a first leg end, the second leg defines a second leg end, and the first leg end and the second leg end flare away from each other.
 5. An air gap insulation system between the rafters of a building, the system comprising: a first rafter hold down clip for installation on a first rafter of predetermined width, the first rafter hold down clip comprising a first substantially flat plate and a first pair of legs extending from the first plate, the first pair of legs each defining a length; a second rafter hold down clip for installation on a second rafter of predetermined width, the second rafter hold down clip comprising a second substantially flat plate and a second pair of legs extending from the second flat plate, the second pair of legs defining the length; and a wrap material secured to the first rafter by the first rafter hold down clip and to the second rafter by the second rafter hold down clip, thereby forming an insulating air gap between the first and second rafter hold down clips of the wrap material.
 6. The system of claim 4, wherein the length of the legs determines a thickness for the insulating air gap.
 7. The system of claim 4, wherein the first pair of legs bow toward each other.
 8. The system of claim 4, wherein the first pair of legs define ends which flare away from each other. 